Multi-tier cellular networks provide significant coverage and capacity improvements over single-layer cellular networks. However, when the tiers of a cellular network are co-channel, they may introduce severe interference to each other.
Some networks place cellular tiers on different bands, which results in poor trunking efficiency and waste of bandwidth. Also, static partitioning of radio resources is wasteful since data traffic usually occurs in bursts. Other networks enforce very low base station density and power level limits to resolve the interference issue, but these measures fail to resolve the interference issue in any efficient manner. As a consequence, the overall throughput is reduced significantly.